A coupling device is known from each of the Patent Abstracts of Japan volume 1998, no. 14 & JP no. 10/259890, and from the European patent specification EP-A-0 794 378.
In JP 10/259890 a sealing ring is used placed directly against a one-piece pressure ring, which pressure ring possesses surfaces that converge in a radial orientation towards each other.
In the coupling device known from EP-A-0 794 378 a sealing organ in the form of a rubber element is provided between on the one side the pressure element, and on the other side a support wall and the tube to be clamped. Furthermore, the pressure element of the prior art coupling device is provided with a friction-increasing surface on the side facing the tube.
When the coupling between the tube and the prior art coupling device comes under strain of tension, the fact that the support element is positioned at an incline, as a result of which it is under extra stress at the side of the pressure element, and will cause the sealing organ, due to the increased clamping force exerted by the pressure element on the tube, to provide an improved sealing action on said tube. The drawback is, however, that the sealing action of the sealing organ between the pressure element and the support element bearing less pressure and being located opposite the support element bearing extra pressure, will deteriorate.